There are conditional commands for MySQL too.
IF/ELSE
SELECT FieldA as A, FieldB as B, IF(FieldA = FieldB, 'equal', 'not equal') as condition, FROM table WHERE this LIKE that
Or cascaded:
SELECT FieldA as A, FieldB as B, IF(FieldA = FieldB,'FieldA is equal to FieldB',IF(FieldC = FieldD,'FieldC is equal to FieldD','all false')) as output, FROM table WHERE this LIKE that